US11577262B2 - Nozzle assembly with auxiliary apertures - Google Patents

Nozzle assembly with auxiliary apertures Download PDF

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US11577262B2
US11577262B2 US15/576,327 US201615576327A US11577262B2 US 11577262 B2 US11577262 B2 US 11577262B2 US 201615576327 A US201615576327 A US 201615576327A US 11577262 B2 US11577262 B2 US 11577262B2
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auxiliary
aperture
air
wall
liquid
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US20180353981A1 (en
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John B. Scheibner
Brian E. Duncan
Elaine M. Yorkgitis
Ryan D. Erickson
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3M Innovative Properties Co
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3M Innovative Properties Co
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/02—Spray pistols; Apparatus for discharge
    • B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
    • B05B7/0807—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets
    • B05B7/0815—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets with at least one gas jet intersecting a jet constituted by a liquid or a mixture containing a liquid for controlling the shape of the latter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/02—Spray pistols; Apparatus for discharge
    • B05B7/06—Spray pistols; Apparatus for discharge with at least one outlet orifice surrounding another approximately in the same plane
    • B05B7/062—Spray pistols; Apparatus for discharge with at least one outlet orifice surrounding another approximately in the same plane with only one liquid outlet and at least one gas outlet
    • B05B7/066—Spray pistols; Apparatus for discharge with at least one outlet orifice surrounding another approximately in the same plane with only one liquid outlet and at least one gas outlet with an inner liquid outlet surrounded by at least one annular gas outlet
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/02—Spray pistols; Apparatus for discharge
    • B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
    • B05B7/0807—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
    • B05B7/02—Spray pistols; Apparatus for discharge
    • B05B7/08—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point
    • B05B7/0807—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets
    • B05B7/0861—Spray pistols; Apparatus for discharge with separate outlet orifices, e.g. to form parallel jets, i.e. the axis of the jets being parallel, to form intersecting jets, i.e. the axis of the jets converging but not necessarily intersecting at a point to form intersecting jets with one single jet constituted by a liquid or a mixture containing a liquid and several gas jets

Definitions

  • nozzle assemblies for a spraying apparatus along with related components, systems and methods. More particularly, the provided nozzle assemblies are for use in handheld spray guns and general spray head assemblies.
  • Spray guns are devices that project a fine mist of particles onto a substrate.
  • a pressurized gas such as air
  • Spray guns can be used to apply to a substrate a wide variety of coating media, including primers, paints, clearcoats, slurries, fine powders, and other sprayable fluids.
  • Notable applications for spray guns include painting and texturizing architectural surfaces such as walls and ceilings, furniture finishing, cosmetics, and painting and body repair for marine and automotive exteriors.
  • Common spray gun configurations use a gun platform that routes compressed air and the liquid to be coated through internal passageways that come together in the vicinity of a spray nozzle.
  • the air and liquid are expelled from the gun through adjacent atomizing and liquid apertures, respectively, comprising the spray nozzle.
  • the fast-moving air flows out of the atomizing apertures through a region of reduced pressure.
  • the air breaks up the liquid from the liquid aperture to form a spray field of fine droplets in a process called atomization.
  • the liquid droplets are propelled toward the surface to be coated.
  • the spray field Before the spray field contacts the substrate, it can be shaped by air jets discharged through precisely positioned orifices (or apertures) in the spray nozzle. These air jets work by re-distributing the spray field proximal to the front face surface of the spray nozzle.
  • Modern spray guns include protruding structures called air horns, which contain one or more pairs of apertures that discharge pressurized air from opposing sides to flatten the spray field, enabling the operator to cover a wider area when applying a coating to a substrate.
  • These spray guns may also include auxiliary air holes, sometimes referred to as “auxiliary apertures” or “secondary apertures,” that direct air outwardly from the front face surface of the spray nozzle. Air from the auxiliary apertures can tailor the air jets from the air horns, increase paint flow rate, and help keep the air cap clean.
  • Auxiliary apertures as disclosed in the art, also present certain technical and manufacturing challenges.
  • a first challenge relates to the locations of the auxiliary apertures, which are generally located at flanking positions alongside the atomizing and liquid apertures. Because air must bend around the central passageways that convey the atomizing air and liquid to be sprayed, the air flow behind the auxiliary apertures is subject to a phenomenon called boundary layer separation. As a result, air flow within the auxiliary apertures can separate from the inside edge surfaces, causing air flow to become skewed within the auxiliary apertures. This in turn can adversely affect the distribution of coating media in the final spray pattern. Control over distribution is especially important in high performance spraying applications.
  • a second challenge relates to mass manufacturing nozzle assemblies through a molding process.
  • auxiliary apertures are drilled into the faceplate (or air cap) of the nozzle assembly and thus have a uniform diameter along their lengths.
  • molding pins are extended through a mold cavity and molten polymer is injected around the pins to define the auxiliary apertures.
  • the outer wall is commonly angled relative to the liquid axis, the molding pin may be asymmetric and precisely registered and rotated to its correct orientation prior to molding. As a result, the process of fabricating, aligning and maintaining the pin is difficult and adds significant cost to the operation.
  • the provided nozzle assemblies, components, systems, and methods address both problems above by using a modified auxiliary aperture where the opening on the inner surface of the air cap is countersunk into the outer wall. This was found to obviate the problems associated with rotatable molding pins and also provide the unexpected advantage of significantly reducing skew in the air flow profile from the auxiliary apertures. Conventionally, a more uniform air flow profile may be obtained by increasing wall thickness in order to lengthen the auxiliary aperture.
  • the provided modification aligns the resultant air flow profile while keeping the length of the auxiliary apertures as low as possible, reducing weight and materials costs while avoiding the kinds of defects associated with relatively thick walls in molded parts.
  • a nozzle assembly for a spraying apparatus comprises: an inner wall having opposed inner and outer surfaces, the inner surface defining a liquid passageway that extends longitudinally along a liquid axis and terminates in a liquid aperture; an outer wall extending around the inner wall and having opposed inner and outer surfaces, wherein the outer surface of the inner wall and inner surface of the outer wall collectively define a first air passageway, the first air passageway terminating in an atomizing aperture adjacent to the liquid aperture; and a pair of auxiliary apertures extending through the outer wall and in communication with the first air passageway, wherein each auxiliary aperture extends along an auxiliary axis and wherein an area of the inner surface of the outer wall adjacent to each auxiliary aperture is countersunk to define a ledge that is axially symmetric about the auxiliary axis.
  • a spraying apparatus comprising: the nozzle assembly as recited above; and a spray gun platform releasably coupled to the nozzle assembly.
  • an air cap for a nozzle assembly of a spraying apparatus comprising: an outer wall having opposed inner and outer surfaces; a central aperture extending through the outer wall; and a pair of auxiliary apertures disposed on the outer wall, each auxiliary aperture aligned along a respective auxiliary axis, wherein an area of the inner surface of the outer wall adjacent to the auxiliary aperture is countersunk to define a ledge that is axially symmetric about the auxiliary axis.
  • a method of aligning auxiliary air flow through the nozzle assembly as recited above comprises: discharging a liquid from the liquid aperture in a conical stream of liquid droplets while simultaneously directing air from the fan control apertures against the discharged liquid from opposing directions to flatten the conical stream of liquid droplets; and directing air from the pair of auxiliary apertures to modify the air flowing from the fan control apertures, wherein each ledge improves axial alignment of the air flow external to its respective auxiliary aperture.
  • a method of making the air cap as recited above from mating core and cavity members comprising: incorporating into either the core or cavity member a pair of cylindrical pins, each having an annular ledge extending along its circumference, the annular ledge having a shape that is complemental to a corresponding ledge on the inner surface of the outer wall; bringing the core and cavity members together in opposing relation to define a mold cavity, wherein a distal end of each cylindrical pin engages an opposing member; and introducing a molten polymer into the mold cavity to form the air cap with each auxiliary aperture defined as an inverse of a respective cylindrical pin, followed by cooling and hardening the polymer melt and releasing the air cap from the mold.
  • FIG. 1 is a perspective view of a spraying apparatus according to an exemplary embodiment, showing its side, rear, and top surfaces;
  • FIG. 2 is a fragmentary cross-sectional side view of a nozzle assembly of the spraying apparatus of FIG. 1 ;
  • FIG. 3 is a perspective view of an air cap of the nozzle assembly of FIG. 2 , showing its front and side surfaces;
  • FIG. 4 is an elevational front view of the air cap of FIG. 3 , showing its front surface;
  • FIG. 5 is a side cross-sectional view of the air cap of FIGS. 3 - 4 ;
  • FIG. 6 is an enlarged fragmentary cross-sectional view of the air cap of FIGS. 3 - 5 corresponding to inset 6 shown in FIG. 5 ;
  • FIGS. 7 A and 7 B are contour images showing simulated air velocity profiles for a conventional nozzle assembly and the provided nozzle assembly of FIGS. 2 - 6 , respectively;
  • FIG. 8 shows an exemplary molding apparatus for manufacturing the air cap of FIGS. 3 - 6 .
  • Pressurized gas refers to gas under greater than atmospheric pressure.
  • Such spray guns include, for example, high volume low pressure spray guns used in automotive, decorative, marine, architectural coating, furniture finishing, scenic painting and cosmetic industries.
  • a spraying apparatus is illustrated in FIG. 1 and designated by the numeral 100 .
  • the spraying apparatus 100 includes a spray gun platform 102 and a nozzle assembly 104 operatively coupled to the spray gun platform 102 .
  • the nozzle assembly 104 is releasably connected to the spray gun platform 102 , allowing the former to be conveniently detached and cleaned.
  • the nozzle assembly 104 is made from plastic and may be discarded or cleaned and re-used at the end of a spraying operation.
  • the nozzle assembly 104 and spray gun platform 102 may be combined as an integral unit.
  • a liquid inlet 106 Extending outwardly from the top of the nozzle assembly 104 is a liquid inlet 106 having a distal end 108 .
  • the distal end 108 has a configuration adapted to releasably connect the liquid inlet 106 to a liquid container (not shown).
  • the spraying apparatus 100 is of the gravity-fed type in which the liquid container is located above the spray gun platform 102 to facilitate gravitational flow of the liquid to be sprayed into the nozzle assembly 104 .
  • the spraying apparatus 100 need not be gravity-fed.
  • the liquid inlet 106 can be connected to a fluid source that is pressurized so that the fluid can be fed from below or any other location.
  • Exemplary liquid containers are previously described, for example, in U.S. Pat. No. 6,588,681 (Rothrum et al.), U.S. Pat. No. 6,663,018 (Rothrum et al.), U.S. Pat. No. 7,188,785 (Joseph et al.), U.S. Pat. No. 7,815,130 (Joseph et al.), and provisional U.S. Patent Application No. 61/912,038 (Nyaribo et al.), filed on Dec. 5, 2013.
  • the liquid inlet 106 is itself incorporated into the nozzle assembly 104 .
  • this avoids the need for extensive cleaning of the spray gun platform 102 between spraying operations.
  • the connecting interface between the nozzle assembly 104 and the spray gun platform 102 enables fluid communication between the interior cavities of these components. Any attachment mechanism known in the art can serve this purpose.
  • the spray gun platform 102 and nozzle assembly 104 are interconnected by an interference fit.
  • the former includes a pair of connection tabs 110 having respective rectangular openings 112 that snugly engage projections 114 located on a barrel 130 of the nozzle assembly 104 .
  • the projections 114 on the nozzle assembly 104 flex inwardly to snap into the openings 112 .
  • the operator pinching buttons 116 in directions toward each other to depress the projections 114 and disengage them from the connection tabs 110 .
  • Locking engagement between the openings 112 and the retaining projections 114 prevents the nozzle assembly 104 from becoming inadvertently detached.
  • other mechanisms can be used, including bayonet-type fixtures, clamps, collars, magnets, and mating threaded connections.
  • the spray gun platform 102 includes a frame 118 , and a pistol-grip handle 120 and trigger 122 connected to the frame 118 .
  • a threaded air inlet port 124 Extending outwardly from the bottom of the handle 120 is a threaded air inlet port 124 for connection to a suitable source of pressurized gas, typically air.
  • the trigger 122 is pivotally connected to the frame 118 and biased toward its forward-most position.
  • a fluid control regulator 126 and fan control regulator 128 can be built into the rear-facing surface of the frame 118 to adjust the rate the coating liquid is dispensed from the nozzle assembly 104 and the pressure of gas flowing from the spray gun platform 102 into the nozzle assembly 104 .
  • the fan control regulator 128 is a rotatable knob that allows an operator to control air flow to a pair of air horns used to adjust the spray pattern geometry.
  • the fluid control regulator 126 adjusts the longitudinal travel distance of a fluid needle associated with a needle valve (not visible) located within the spraying apparatus 100 . The travel of the fluid needle can affect both fluid flow and air flow. Depressing the trigger 122 actuates the needle valve and dispenses the coating liquid from the spraying apparatus 100 .
  • FIGS. 2 and 3 provide alternative views showing features of the nozzle assembly 104 and its components in more detail.
  • the nozzle assembly 104 includes the barrel 130 and an air cap 132 engaged to the front, or working end, of the barrel 130 .
  • the air cap 132 is rotatably coupled to the working end of the barrel 130 in encircling relation, permitting a 90-degree range of relative rotation between these components.
  • the air cap 132 could be fixed relative to the barrel 130 or even formed as an integral component of the barrel 130 .
  • a pair of concentric apertures Centrally disposed on the front surface of the nozzle assembly 104 are a pair of concentric apertures: a circular liquid aperture 134 and an annular atomizing aperture 136 adjacent to, and surrounding, the liquid aperture 134 .
  • the apertures 134 , 136 are separated by a generally cylindrical inner wall 140 of the barrel 130 .
  • each of the apertures 134 , 136 and inner wall 140 are concentrically disposed about a liquid axis 138 , shown in FIGS. 2 and 4 .
  • the apertures may vary in shape, size, and relative orientation from that depicted here.
  • the atomizing aperture 136 need not be annular and may only partially surround the liquid aperture 134 .
  • two or more liquid apertures 134 or atomizing apertures 136 could be implemented if so desired.
  • a liquid passageway 142 defined by inner surfaces of the inner wall 140
  • a first air passageway 144 defined by the annular space between the inner wall 140 and an outer wall 146 of the air cap 132 , extend longitudinally along the liquid axis 138 .
  • the liquid passageway 142 and first air passageway 144 initiate at the rear end of the nozzle assembly 104 and terminate at the liquid aperture 134 and atomizing aperture 136 , respectively.
  • the passageways 142 , 144 have volumetric shapes generally symmetric about the liquid axis 138 in the vicinity of the apertures 134 , 136 .
  • the outer wall 146 of the air cap 132 whose exterior surface is visible in FIG. 3 , extends around the inner wall 140 and defines outermost surfaces of the first air passageway 144 .
  • the outer wall 146 is cylindrically shaped in this embodiment, although other shapes are also possible.
  • the trigger 122 When the trigger 122 is depressed, air is injected under pressure through the rear end of the nozzle assembly 104 and accelerates as it enters regions of decreasing cross-section before being expelled from the atomizing aperture 136 . Based on the Venturi effect, this results in a pressure drop in front of the liquid aperture 134 , which can help draw fluid to be sprayed out of the liquid passageway 142 and through the liquid aperture 134 . Upon encountering the moving air, the coating fluid is then atomized—that is, pulverized into many fine droplets. In parallel, the liquid may also be urged through the liquid aperture 134 by gravity or by pressurizing the liquid within the liquid container.
  • a pair of air horns 148 extend outwardly in the forward direction from the air cap 132 and protrude past both the liquid aperture 134 and atomizing aperture 136 .
  • the air horns 148 are integrally formed as part of the air cap 132 , standing as mirror images of each other on opposite sides of the liquid axis 138 .
  • Each air horn 148 defines a respective air horn cavity in communication with a second air passageway 150 that terminates in a generally circular inner fan control aperture 152 and adjacent outer fan control aperture 154 .
  • the fan control apertures 152 , 154 extend through the external surface of the air horn 148 and serve to discharge pressurized air from the second air passageway 150 .
  • each air horn 148 may be present on only one fan control aperture.
  • either or both of the fan control apertures 152 , 154 may assume non-circular shapes, as described in U.S. Pat. No. 7,201,336 (Blette et al.).
  • the air horns 148 enable simultaneous air flow from the fan control apertures 152 , 154 against the fluid stream from opposing directions to flatten the airborne spray profile and improve operator control over the resulting spray pattern.
  • the air pressure driving the flow of air from the fan control apertures 152 , 154 is independently regulated from the air pressure used to atomize the fluid to be dispensed from the spraying apparatus 100 .
  • this can be achieved when the atomizing aperture 136 and fan control apertures 152 , 154 are isolated from each other within the nozzle assembly 104 .
  • This can be achieved using discrete first and second air passageways 144 , 150 having internal air pressures that are independently regulated, thus allowing a pressure differential to be maintained between them.
  • the same volume of pressurized air can be used for both of the functions above; for example, the first and second air passageways 144 , 150 can be in communication with each other within the nozzle assembly 104 .
  • both of the first and second air passageways 144 , 150 could communicate with a common plenum adjacent to the interface between the spray gun platform 102 and nozzle assembly 104 .
  • the first and second air passageways 144 , 150 would be in fluid communication, enabling both passageways 144 , 150 to be pressurized using a single conduit on the spray gun platform 102 .
  • the apportionment of air flowing into the nozzle assembly 104 can also be controlled, at least in part, by the geometry of the first and second air passageways 144 , 150 .
  • the outer wall 146 includes a front-facing wall section 156 .
  • Extending through the wall section 156 is a pair of auxiliary apertures 158 flanking the liquid aperture 134 and atomizing aperture 136 .
  • the auxiliary apertures 158 are diametrically opposed with respect to the liquid axis 138 and are aligned such that they are coplanar with the fan control apertures 152 , 154 of respective air horns 148 .
  • the auxiliary apertures 158 could be slightly out of plane yet sufficiently close to influence the shaping air jets emitted from the fan control apertures 152 , 154 .
  • FIGS. 4 - 6 the air cap 132 is shown having a central aperture 160 disposed in its wall section 156 .
  • the edges of the central aperture 160 define the circumferential outer edge of the atomizing aperture 136 when the nozzle assembly 104 is assembled.
  • the auxiliary apertures 158 are aligned with respective auxiliary axes 162
  • the fan control apertures 152 , 154 are aligned with respective fan control axes 194 , 196 .
  • the auxiliary axes 162 intersect with the fan control axes 194 , 196 and extend along directions transverse to those of the fan control axes 194 , 196 .
  • the auxiliary axes 162 extend in directions parallel to the liquid axis 138 . If desired, however, the auxiliary axes 162 may be angled slightly from the liquid axis 138 .
  • each ledge 166 has an annular shape that is axially symmetric about the auxiliary axis 162 of its respective auxiliary aperture 158 .
  • each ledge 166 is generally planar and extends along a plane that is perpendicular to the respective auxiliary axis 162 .
  • the ledges 166 may be somewhat angled relative to the auxiliary axis 162 , such angle being at least 45 degrees, at least 55 degrees, at least 65 degrees, at least 75 degrees, at least 80 degrees, or at least 85 degrees. In one such variant, for example, the ledges 166 coincide with a conical, rather than a planar, surface.
  • each ledge 166 represents a portion of the inner surface 164 that bridges a cylindrical side wall 170 of the auxiliary aperture 158 (characterized by a certain radius R 1 ) with the peripheral surface 167 of a cavity adjacent to the auxiliary aperture 158 .
  • the peripheral surface 167 generally revolves about, and is coaxial with, the auxiliary axis 162 and characterized by an enlarged radius R 2 , where R 2 is greater than R 1 .
  • the ledge 166 could be planar, convex, or concave, and have any of a number of angular orientations relative to the auxiliary axis 162 .
  • auxiliary apertures 158 may have side walls that are not cylindrical.
  • the corresponding side walls 170 could have a tapered or a truncated conical configuration.
  • each auxiliary aperture 158 has an annular edge defined at the interface between the side wall 170 and the ledge 166 , the annular edge having a corner radius of at least 1 percent, at least 2 percent, at least 4 percent, at least 6 percent, or at least 8 percent of the radius R 1 .
  • the annular edge has a corner radius of at most 25 percent, at most 50 percent, at most 75 percent, at most 150 percent, or at most 300 percent of the radius R 1 .
  • the annular edge extends along the geometric center of the convex areas associated with the corner radius above.
  • auxiliary apertures 158 e.g. diameter
  • the corresponding ledge 166 need not have an annular shape.
  • the ledge 166 could become crescent-shaped instead of annular.
  • the surface of such a ledge 166 is preferably inscribed within an annular ring having axial symmetry about the auxiliary axis 162 .
  • each ledge 166 has a certain maximum width W, as measured along a radial direction perpendicular to the auxiliary axis 162 .
  • maximum width W can also be represented as the difference between R 1 and R 2 (i.e., R 2 -R 1 ).
  • the maximum width W in some embodiments, can be at least 10 percent, at least 20 percent, at least 30 percent, at least 40 percent, or at least 50 percent of the radius R 1 of the auxiliary aperture 158 .
  • the maximum width W can be at most 70 percent, at most 90 percent, at most 110 percent, at most 130 percent, at most 150 percent, or at most 300 percent of the radius R 1 .
  • each auxiliary aperture 158 is located on an area of an outer surface 168 of the wall section 156 that is generally planar and oriented perpendicular to the auxiliary axis 162 . Because both the inner surface 164 and outer surface 168 of the wall section 156 are perpendicular to the auxiliary axis 162 , the side wall 170 of the auxiliary aperture 158 has an axial length that is generally constant along its circumference. This need not be the case, however, particularly if the auxiliary aperture 158 is angled to some extent relative to the wall section 156 .
  • a suitable corner radius may be implemented between each ledge 166 and its adjacent side wall 170 . While such a corner radius narrows the annular ledge 166 , this was not found to compromise the performance of the nozzle assembly 104 when used in the spraying apparatus 100 .
  • Areas of the inner surface 164 of the wall section 156 outside the perimeter of the ledges 166 have a generally conical shape symmetric about the liquid axis 138 .
  • Air emitted from the auxiliary apertures 158 interacts with the air emitted from the fan control apertures 152 , 154 to flatten and re-distribute the atomized spray field.
  • the ledges 166 present on the inner surface 164 of the nozzle assembly 104 were discovered to provide important technical advantages.
  • this configuration improves axial alignment of the air flow both through the auxiliary apertures 158 and external to the air cap 132 compared with analogous configurations of the nozzle assembly 104 that are missing the ledges 166 .
  • This improvement is evident in FIGS. 7 A and 7 B , showing simulated air flow profiles of a conventional nozzle assembly and one including the ledges 166 as described in the Examples section below.
  • FIG. 8 shows an exemplary molding assembly 180 .
  • the molding assembly 180 is comprised of a cavity member 182 and a mating core member 184 .
  • the core member 184 includes a main body 185 and a pair of pins 186 slidably received in respective guide holes 188 extending through the main body 185 .
  • the ends of the pins 186 act as mold shut-offs and are received in pilot features 190 .
  • the pilot features 190 are blind holes have configurations that mate with the distal ends of the pins 186 .
  • the pins 186 define the shapes of the auxiliary apertures 158 and ledges 166 .
  • the pins 186 can thus adopt any orientation within the guide holes 188 provided that their distal ends abut against the pilot features 190 .
  • the distal ends of the pins 186 are tapered to present respective sloping side walls.
  • the sloping side wall may have any particular angle that helps guide the distal ends into their corresponding pilot features 190 .
  • the sloping side wall is oriented at an angle ranging from 40 to 50 degrees with respect to the longitudinal axis of its respective cylindrical pin 186 .
  • a butt shut-off configuration may be used where the pins 186 are pressed against opposing surfaces of the cavity member 182 without need for a pilot feature.
  • any of the mold surfaces described herein may optionally have drafts of a few degrees incorporated to facilitate removal of parts from the mold.
  • the foregoing fabrication process can also mitigate defects that arise from molding thick walled parts, such as shrinkage-related defects.
  • a nozzle assembly for a spraying apparatus including:
  • an inner wall having opposed inner and outer surfaces, the inner surface defining a liquid passageway that extends longitudinally along a liquid axis and terminates in a liquid aperture;
  • each auxiliary aperture extends along an auxiliary axis and wherein an area of the inner surface of the outer wall adjacent to each auxiliary aperture is countersunk to define a ledge that is axially symmetric about its auxiliary axis.
  • each auxiliary aperture has a cylindrical side wall whose length, defined along its longitudinal axis, is generally constant along the circumference of the auxiliary aperture.
  • the nozzle assembly of embodiment 1 or 2 further including a pair of diametrically opposed air horns protruding past the liquid aperture from the outer wall and defining respective air horn cavities in communication with a second air passageway, each air horn having an external wall and at least one fan control aperture extending along a fan control axis through the external wall to direct air from the air horn cavity against a stream of liquid droplets discharged from the liquid aperture, each auxiliary axis aligned transverse to a respective fan control axis. 4.
  • each auxiliary aperture has a certain radius and the ledge has a certain maximum width as measured along a radial direction perpendicular to the auxiliary axis, the certain maximum width ranging from 10 percent to 300 percent of the certain radius. 10.
  • each auxiliary aperture extends through a portion of the outer surface of the outer wall that is generally planar and has an orientation perpendicular to the liquid axis.
  • each auxiliary aperture has an annular edge defined along the area of the inner surface of the outer wall, the annular edge having a corner radius ranging from 1 percent to 300 percent of the radius of the auxiliary aperture.
  • each ledge improves axial alignment of the air flow external to its respective auxiliary aperture.
  • a spraying apparatus including:
  • a spray gun platform releasably coupled to the nozzle assembly.
  • An air cap for a nozzle assembly of a spraying apparatus including:
  • each auxiliary aperture aligned along a respective auxiliary axis, wherein an area of the inner surface of the outer wall adjacent to the auxiliary aperture is countersunk to define a ledge that is axially symmetric about the auxiliary axis.
  • a pair of cylindrical pins each having an annular ledge extending along its circumference, the annular ledge having a shape that is complemental to a corresponding ledge on the inner surface of the outer wall;
  • each auxiliary aperture defined as an inverse of a respective cylindrical pin.
  • the Example is based on the geometry shown in FIG. 7 A and used an auxiliary aperture diameter of 0.030 inches (0.75 millimeters).
  • the Comparative is based on the geometry shown in FIG. 7 B , which was essentially the same except for the absence of countersunk ledges—i.e., areas of the inner surface immediately adjacent to each auxiliary aperture were not countersunk but rather flush with the conical inner surface of the outer wall.
  • FLUENT available from ANSYS, Inc., Canonsburg, Pa.
  • FLUENT available from ANSYS, Inc., Canonsburg, Pa.
  • the model was implemented to predict air flow behavior within the system. Compressibility effects of the gas were included in the model.
  • This model contained approximately 7 million cells.
  • the “Pressure-Based Coupled Solver” was used along with the pseudo-transient solution method and was found to enable a steady state solution with good stability.
  • the turbulence model used was the Realizable K-e model with enhanced wall treatment. Boundary conditions for the domain are given in Table 1. Flow rates for shaping air passages were set to approximately 50% of total air flow. Boundary conditions remain constant for each model, so that the only modification made between models shows the effect of geometry changes.
  • Contour images corresponding to the Example and the Comparative are shown in FIGS. 7 A and 7 B , respectively.
  • the inclusion of the countersunk ledges adjacent to the auxiliary apertures resulted in improved axial alignment of the air flow both within the auxiliary apertures and in the space in front of the auxiliary apertures.

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  • Nozzles (AREA)
  • Spray Control Apparatus (AREA)
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FR3048896B1 (fr) 2016-03-21 2018-04-13 Exel Industries Pulverisateur de produit de revetement, procede de montage et de demontage
JP7149270B2 (ja) 2016-12-06 2022-10-06 スリーエム イノベイティブ プロパティズ カンパニー スプレーガン及びノズルアセンブリの取り付け
WO2018104826A1 (en) 2016-12-06 2018-06-14 3M Innovative Properties Company Paint spray gun coating liquid connector
CN108940630A (zh) * 2018-07-13 2018-12-07 安徽康瑞高科新材料技术工程有限公司 一种新型涂料喷头

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CA2987200A1 (en) 2016-12-01
JP2018515336A (ja) 2018-06-14
EP3302818B1 (en) 2021-05-05
CN107660163B (zh) 2021-02-05
MX2017014883A (es) 2018-04-20
CN107660163A (zh) 2018-02-02
EP3302818A1 (en) 2018-04-11
AU2016267026A1 (en) 2017-12-07
AU2016267026B2 (en) 2019-07-11
US20180353981A1 (en) 2018-12-13
WO2016191240A1 (en) 2016-12-01
JP6789987B2 (ja) 2020-11-25

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